My Suzuki RG125F Project
Discussion
Yazza54 said:
Does the bike have an oil pump or is your intention to mix?
It has an oil pump, I'm not intending to pre-mix.ETA: I didn't realise you were in this neck of the woods, I've been following your Mito build and it looks bloody awesome!
Edited by D-Angle on Thursday 13th August 22:13
D-Angle said:
Yazza54 said:
Does the bike have an oil pump or is your intention to mix?
It has an oil pump, I'm not intending to pre-mix.ETA: I didn't realise you were in this neck of the woods, I've been following your Mito build and it looks bloody awesome!
Edited by D-Angle on Thursday 13th August 22:13
Oil pump is definitely the way to go, it's the only way to make sure the engine gets the right amount of oil for a given throttle input/revs... Plus it's a f
k tonne less messing about!!!It's been a while.
Other time pressures have slowed progress, I'm still working on the engine and so far I have managed:
- new clutch and clutch basket
- new gaskets throughout
- rebuilt the powervalves
- pulled out the reeds, which look fine so keeping those
- about to helicoil 2 stripped threads on the crankcase, soon as the kit shows up
I have done most of what I want to, I just have a loose head bolt to sort out, and I am considering replacing the stator and could use some opinions. Observe:
The insulating cover looks tatty as hell, I'm also not sure what this thing is sitting between 2 of the coils:
This wire looks a little dark, possibly shorted?
Any thoughts/suggestions appreciated.
Other time pressures have slowed progress, I'm still working on the engine and so far I have managed:
- new clutch and clutch basket
- new gaskets throughout
- rebuilt the powervalves
- pulled out the reeds, which look fine so keeping those
- about to helicoil 2 stripped threads on the crankcase, soon as the kit shows up
I have done most of what I want to, I just have a loose head bolt to sort out, and I am considering replacing the stator and could use some opinions. Observe:
The insulating cover looks tatty as hell, I'm also not sure what this thing is sitting between 2 of the coils:
This wire looks a little dark, possibly shorted?
Any thoughts/suggestions appreciated.
Looks fine to me. Measure the resistance/continuity between the output wires and if it checks out then leave it.
While they do sometimes fail it's not a common failing, more often than not its the reg/rec or the wiring from the stator to the reg/rec and I'd pay more attention to that connector and make sure it's cleaned and lubed to prevent corrosion.
While they do sometimes fail it's not a common failing, more often than not its the reg/rec or the wiring from the stator to the reg/rec and I'd pay more attention to that connector and make sure it's cleaned and lubed to prevent corrosion.
Oh bugger.
Tightening the cylinder head nuts today and one of the studs starts coming out of the cylinder as I turn, the required tightness being too much for the stud to stay in place.
I pop the head back off, and go to remove the stud to inspect it, only to find it is wobbling around in the hole while I do it. I get it out and this comes with it:
Holy Helicoil Batman!!
It looks like tightening up the head nut caused the helicoil to finally give up the ghost and come loose. There is some threading still in the hole but I'm not able to get the stud to catch onto it, so I'm guessing that's the thread for the helicoil.
So what are my options? Can I re-helicoil this? or is my cylinder screwed?
Tightening the cylinder head nuts today and one of the studs starts coming out of the cylinder as I turn, the required tightness being too much for the stud to stay in place.
I pop the head back off, and go to remove the stud to inspect it, only to find it is wobbling around in the hole while I do it. I get it out and this comes with it:
Holy Helicoil Batman!!
It looks like tightening up the head nut caused the helicoil to finally give up the ghost and come loose. There is some threading still in the hole but I'm not able to get the stud to catch onto it, so I'm guessing that's the thread for the helicoil.
So what are my options? Can I re-helicoil this? or is my cylinder screwed?
i had two 125 gammas as a teenager, the first one was standard and got nicked. the second was tuned to within an inch of its life ,god knows how many time it got rebuilt. think the main jet went up from a 95 as standard to a 260 !
looks like it has the usual teenage bodge jobs all small two strokes seem to come with, does look in amazing condition overall for the age though. mine were the previous model, both 1986 bikes.
your cylinder head looks as though there have been serious detonation issues to me,never seen a two stoke cylinder head that was anything but smooth,stand to be corrected though. all the high spots at the edge of those small depressions will heat up and cause pre ignition if run like that i would have thought. looks like the second oversize piston as well, so it is likely it has been rebored at least twice. if so it might be worth a complete overhaul, crank seals as suggested already plus main bearings ,a new piston kit and gasket set.the barrel does not look standard,someone been in there with a file and not one of the recognised tuners by the look of it.
again as already mentioned, get a new set of reeds , if it is still on the standard ones they will be shot by now.
not a clue about the electrics, my sparky mate did all electrickery when any of us had a problem back in the day. you will have a load of fun working on it and learn a fair bit. will be a great laugh once up and running. i had a go on a mates nsr 125 a couple of years ago and could not stop smiling, every biker should have a two stroke 125 in the garage for days when they need cheering up.
looks like it has the usual teenage bodge jobs all small two strokes seem to come with, does look in amazing condition overall for the age though. mine were the previous model, both 1986 bikes.
your cylinder head looks as though there have been serious detonation issues to me,never seen a two stoke cylinder head that was anything but smooth,stand to be corrected though. all the high spots at the edge of those small depressions will heat up and cause pre ignition if run like that i would have thought. looks like the second oversize piston as well, so it is likely it has been rebored at least twice. if so it might be worth a complete overhaul, crank seals as suggested already plus main bearings ,a new piston kit and gasket set.the barrel does not look standard,someone been in there with a file and not one of the recognised tuners by the look of it.
again as already mentioned, get a new set of reeds , if it is still on the standard ones they will be shot by now.
not a clue about the electrics, my sparky mate did all electrickery when any of us had a problem back in the day. you will have a load of fun working on it and learn a fair bit. will be a great laugh once up and running. i had a go on a mates nsr 125 a couple of years ago and could not stop smiling, every biker should have a two stroke 125 in the garage for days when they need cheering up.
s3fella said:
Time for a Timesert? may be a squeeze, but should get one in.
Timeserts look good but expensive, I have ordered a helicoil kit and a new stud, I'll see how it looks once I have those to offer up to the hole and make a decision then.wc98 said:
your cylinder head looks as though there have been serious detonation issues to me,never seen a two stoke cylinder head that was anything but smooth,stand to be corrected though. all the high spots at the edge of those small depressions will heat up and cause pre ignition if run like that i would have thought.
I hadn't thought anything of the 'dappled' finish, I had assumed it was the natural finish from the casting process. I'm struggling to find a picture of another one for comparison but I'l look into it more, thanks for pointing that out. 
All the necessary bits arrived this morning, thanks to www.pjme.co.uk for getting it all out to me so quickly.
The drillbit that came with the helicoiliing kit goes most of the way into the hole. However the tap doesn't go in very far at all, suggesting there's enough material to cut a thread for the helicoil.
Old stud, meet new stud:
Yep, knackered.
The drillbit that came with the helicoiliing kit goes most of the way into the hole. However the tap doesn't go in very far at all, suggesting there's enough material to cut a thread for the helicoil.
Old stud, meet new stud:
Yep, knackered.
Well the helicoiling appears to have been successful, pending refitting of the cylinder. But like everything else, it wasn't that straightforward.
I rigged this up to make sure I drilled the hole as square and straight as possible:
That drill stand by the way is £15 in Lidl and well worth getting, you'll never realise how much you wanted your own drill press.
After the old helicoil came out I was able to find enough material to cut a thread for a new one, but it was further down in the hole compared with the old thread. You can see the remains of the old thread at the top, and the new helicoil below:
So, inevitably, the new stud sat much lower than originally intended (far left), with barely any visible thread once the head was installed:
After much searching, and much ribbing from Mrs D-Angle about searching the internet for a long stud, I found a stud that would fit that was 12mm longer. This new stud is on the right in the photos, I decided to replace the stud on the other side with the standard stud that I had already bought. Waste not, want not. :
I still have to see if everything torques down, but it feels as secure as the rest of the studs so I'm quietly confident.
I also decided to revisit the combustion chamber as it was mentioned previously that it shouldn't have such a 'dimpled' finish. I needed something to move the head in a circular motion so I could smooth the chamber with increasingly fine pieces of abrasive paper. So I put this together:
That's an electric screwdriver, clamped to a bench, with a couple of adaptors to fit a sparkplug socket, which is holding the plug, to turn the head around the axis of the centre of the cylinder. I'm not proud of myself, but it seems to have worked.
It's not perfect, but it's a damn sight better than it was.
I have some new reeds on the way,and once they're fitted the engine is going back in and we'll see if it will start. After that I will be looking at the suspension and brakes; I learned recently that a popular upgrade for the RG is to fit the rear shock from the SV650, which fits with minor modification. So that's a possibility. Engine first though!
I rigged this up to make sure I drilled the hole as square and straight as possible:
That drill stand by the way is £15 in Lidl and well worth getting, you'll never realise how much you wanted your own drill press.
After the old helicoil came out I was able to find enough material to cut a thread for a new one, but it was further down in the hole compared with the old thread. You can see the remains of the old thread at the top, and the new helicoil below:
So, inevitably, the new stud sat much lower than originally intended (far left), with barely any visible thread once the head was installed:
After much searching, and much ribbing from Mrs D-Angle about searching the internet for a long stud, I found a stud that would fit that was 12mm longer. This new stud is on the right in the photos, I decided to replace the stud on the other side with the standard stud that I had already bought. Waste not, want not.
:I still have to see if everything torques down, but it feels as secure as the rest of the studs so I'm quietly confident.
I also decided to revisit the combustion chamber as it was mentioned previously that it shouldn't have such a 'dimpled' finish. I needed something to move the head in a circular motion so I could smooth the chamber with increasingly fine pieces of abrasive paper. So I put this together:
That's an electric screwdriver, clamped to a bench, with a couple of adaptors to fit a sparkplug socket, which is holding the plug, to turn the head around the axis of the centre of the cylinder. I'm not proud of myself, but it seems to have worked.
It's not perfect, but it's a damn sight better than it was.
I have some new reeds on the way,and once they're fitted the engine is going back in and we'll see if it will start.
After that I will be looking at the suspension and brakes; I learned recently that a popular upgrade for the RG is to fit the rear shock from the SV650, which fits with minor modification. So that's a possibility. Engine first though!'Scuse me posting at such an ungodly hour, but I just finished reassembling the motor, everything torques down, and I'm very chuffed about that. 
I still have to put the motor back in in the frame and take a good long look at the carb and the ignition system, but there is definitely some progress made. I put some carbon reeds in:
And my SV650 shock arrived ready for the next stage once the motor is done.
I still have to put the motor back in in the frame and take a good long look at the carb and the ignition system, but there is definitely some progress made. I put some carbon reeds in:
And my SV650 shock arrived ready for the next stage once the motor is done.
MotorsportTom said:
Why not be proud of yourself for rigging up the screwdriver/head jig?
There is a fine line between genius and stupidity. If it worked it wasn't stupid...
Also looks like great progress thus far, keep it up! I'm looking forward to seeing the finished article
http://www.strategypage.com/humor/articles/military_humor_murphys_laws_of_combat.aspThere is a fine line between genius and stupidity. If it worked it wasn't stupid...
Also looks like great progress thus far, keep it up! I'm looking forward to seeing the finished article
Rule 6
cirian75 said:
MotorsportTom said:
Why not be proud of yourself for rigging up the screwdriver/head jig?
There is a fine line between genius and stupidity. If it worked it wasn't stupid...
Also looks like great progress thus far, keep it up! I'm looking forward to seeing the finished article
http://www.strategypage.com/humor/articles/military_humor_murphys_laws_of_combat.asp There is a fine line between genius and stupidity. If it worked it wasn't stupid...
Also looks like great progress thus far, keep it up! I'm looking forward to seeing the finished article
Rule 6
Looking good!
Bear in mind that grinding out the detonation damage from the head will have lowered the compression a little.
Good excuse to do away with the head gasket and just lap the head directly to the barrel with some valve grinding paste, old school tuning style.
Come to think of it, don't really do that; it might cause even more detonation.
Bear in mind that grinding out the detonation damage from the head will have lowered the compression a little.
Good excuse to do away with the head gasket and just lap the head directly to the barrel with some valve grinding paste, old school tuning style.
Come to think of it, don't really do that; it might cause even more detonation.
Since my last update Ihave pretty much spent all this time trying to get it to start, found that I have no spark and have been trying to isolate the problem. So far think it's not one thing but several.
First up, the ignition coil. Continuity test from the far side of the coil to the spark plug cap failed, so a new one is to be acquired. Secondly, a test of the CDI unit using the handy graph in my manual suggests that it is comprehensively shafted. Neither item is technically difficult to replace, it will just mean sourcing them and paying for them. Failing that I'm calling a witchdoctor...
First up, the ignition coil. Continuity test from the far side of the coil to the spark plug cap failed, so a new one is to be acquired. Secondly, a test of the CDI unit using the handy graph in my manual suggests that it is comprehensively shafted. Neither item is technically difficult to replace, it will just mean sourcing them and paying for them. Failing that I'm calling a witchdoctor...
Still trying for that first start I'm afraid. 
The no spark problem turned out to be the CDI box, after much searching I tracked down a replacement in France, fitted that and replaced the coil while I was at it. Presto, a spark!
I stripped and cleaned the carb so there should be no fuelling issues, however the spark plug isn't wet when I take it out after trying to start it. I have finally performed a compression test and got 100 psi. Everything I can find suggests I should be getting a minimum of 110 psi in a healthy engine. It would explain no fuel too, as with no compression the fuel won't be drawn into the cylinder.
So as far as the holy trinity of fuel, spark and compression goes, it appears she had... none of the above. Is there any way to tell if the compression problem is being caused by the piston rings or the crank seals? The rings looked OK when I pulled the cylinder off, crankshaft seals will mean pulling the motor out again and completely disassembling it, which I will do but only if necessary.
The no spark problem turned out to be the CDI box, after much searching I tracked down a replacement in France, fitted that and replaced the coil while I was at it. Presto, a spark! I stripped and cleaned the carb so there should be no fuelling issues, however the spark plug isn't wet when I take it out after trying to start it. I have finally performed a compression test and got 100 psi. Everything I can find suggests I should be getting a minimum of 110 psi in a healthy engine. It would explain no fuel too, as with no compression the fuel won't be drawn into the cylinder.
So as far as the holy trinity of fuel, spark and compression goes, it appears she had... none of the above. Is there any way to tell if the compression problem is being caused by the piston rings or the crank seals? The rings looked OK when I pulled the cylinder off, crankshaft seals will mean pulling the motor out again and completely disassembling it, which I will do but only if necessary.
Gassing Station | Biker Banter | Top of Page | What's New | My Stuff